Dual-flow exhaust systems having two exhaust conduits directing exhaust gases away from an internal combustion engine may be used in a variety of engines. It may be particularly beneficial to use a dual-flow exhaust system in an engine having a V cylinder configuration, due to the layout and packaging of the engine components. The benefits include increased engine compactness and improved engine performance.
Acoustic attenuation devices, such as resonators and mufflers, have been designed to reduce and in some cases eliminate acoustic frequencies in dual-flow exhaust streams. Exhaust systems employing a pair of resonators have been designed to attenuate acoustic frequencies present in dual-flow exhausts. For example, in U.S. Pat. No. 4,408,675 an exhaust system with a resonator coupled to each exhaust stream is disclosed. However, there may be several shortcomings with this type of design. The cost of the vehicle may be increased when multiple resonators are utilized as opposed to a single resonator. Furthermore the size of the exhaust system may be increased when multiple resonators are utilized.
Attempts have been made to use a single resonator to attenuate acoustic frequencies in both exhaust streams of dual-flow exhaust systems. For example a resonator having two exhaust conduits communicating through two horizontally opposed opening that are fluidly coupled to a neck is disclosed US 2009/0301807. Exhaust gases may flow into the sealed resonator enclosure (i.e., neck-body) from either exhaust conduit via the horizontally opposed opening. In turn, sound waves are transferred to the resonator of which a portion are reflected off the walls of the housing and neck body and attenuated.
The inventors have recognized several issues with the exhaust system disclosed in US 2009/0301807. For example, the configuration of the disclosed resonator, in particular the positioning of the opening, increases back pressure in the exhaust stream degrading engine efficiency. Moreover, a limited range of frequencies may be attenuated due to the spatial constraints of the neck body. Other dual-flow single enclosure resonator designs also involve trade-offs between the amount of acoustic attenuation provided by the resonator and back-pressure generated by the device.
As such, various example systems and approaches are described herein. For example, a resonator for a dual-flow exhaust system of an engine is provided. The resonator includes a housing defining an enclosure and a baffle spanning the housing and separating a first and a second expansion chamber of the enclosure, the baffle including at least one opening. The resonator further includes a first and a second exhaust conduit extending through the baffle and housing, each conduit in fluidic communication with a separate cylinder bank and including a perforated portion fluidly coupled to the enclosure, each perforated portion positioned in separate expansion chambers.
It will be appreciated that the opening in the baffle enables fluidic communication between the first and second expansion chambers to attenuate a targeted frequency or frequency range without unduly increasing the back pressure. The opening may increase frequency attenuation when compared to resonators designed without an opening. It will be appreciated that the size of the opening may be independently tuned to attenuate a desired frequency or frequency range without increasing losses within the exhaust system.
This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to implementations that solve any or all disadvantages noted in any part of this disclosure.